When a primary user and a secondary user sharing and using a frequency in wireless communication are present, an use of the primary user needs to be protected from a frequency interference by the secondary user. For example, a wireless device of the secondary user using a TV white space needs to use a frequency while protecting a DTV service of the primary user without causing frequency interference with a DTV receiver of the primary user or a permissible wireless mike which is the existing service in a TV band. To this end, the secondary user needs to use the frequency, having a protective distance, so as to prevent a wireless signal transmitted by the secondary user from arriving at the place where the primary user is present so as not to cause frequency interference with the DTV service of the primary user.
That is, the protective distance needs to be accurately calculated, and a coverage of the wireless signal transmitted from the wireless device of the secondary user, that is, a radio coverage needs to be considered at the time of calculating the protective distance. Even though the wireless signal transmitted from the wireless device of the secondary user arrives at a receiver of the primary user, the wireless signal arrives at power which is smaller than radio power having an effect of frequency interference to rule out the effect of frequency interference. Here, a distance at which the wireless signal transmitted from a transmitter of the secondary user arrives at the power which is smaller than the radio power that may cause frequency interference to the primary user is the protective distance. Therefore, to protect the primary user, there is a need to accurately calculate the radio coverage of the wireless signal generated due to the secondary user. For this purpose, there is a need to accurately calculate a height of an antenna of the secondary user.